package com.credly.newsfreak.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.Stack;
import java.util.WeakHashMap;

import com.credly.newsfreak.R;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;

public class ImageLoader
{

	MemoryCache memoryCache = new MemoryCache();
	FileCache fileCache;
	private Map<ImageView, String> imageViews = Collections
			.synchronizedMap(new WeakHashMap<ImageView, String>());

	public ImageLoader(Context context) {
		// Make the background thead low priority. This way it will not affect
		// the UI performance
		photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);

		fileCache = new FileCache(context);
	}

	final int stub_id = R.drawable.newsfreakicon;

	public void DisplayImage(String url, Activity activity, ImageView imageView)
	{
		imageViews.put(imageView, url);
		Bitmap bitmap = memoryCache.get(url);
		if (bitmap != null)
			imageView.setImageBitmap(bitmap);
		else
		{
			queuePhoto(url, activity, imageView);
			imageView.setImageResource(stub_id);
		}
	}

	private void queuePhoto(String url, Activity activity, ImageView imageView)
	{
		// This ImageView may be used for other images before. So there may be
		// some old tasks in the queue. We need to discard them.
		photosQueue.Clean(imageView);
		PhotoToLoad p = new PhotoToLoad(url, imageView);
		synchronized (photosQueue.photosToLoad)
		{
			photosQueue.photosToLoad.push(p);
			photosQueue.photosToLoad.notifyAll();
		}

		// start thread if it's not started yet
		if (photoLoaderThread.getState() == Thread.State.NEW)
			photoLoaderThread.start();
	}

	private Bitmap getBitmap(String url)
	{
		Bitmap bitmap = null;
		try
		{
			File f = fileCache.getFile(url);

			// from SD cache
			if (f != null )
			{
				Bitmap b = decodeFile(f);

				if (b != null)
					return b;

				// from web

				URL imageUrl = new URL(url);
				HttpURLConnection conn = (HttpURLConnection) imageUrl
						.openConnection();
				conn.setConnectTimeout(30000);
				conn.setReadTimeout(30000);
				InputStream is = conn.getInputStream();
				OutputStream os = new FileOutputStream(f);
				Utils.CopyStream(is, os);
				os.close();
				bitmap = decodeFile(f);
				return bitmap;
			}
		} catch (Exception ex)
		{
			ex.printStackTrace();
			return null;
		}
		return bitmap;

	}

	// decodes image and scales it to reduce memory consumption
	private Bitmap decodeFile(File f)
	{
		try
		{
			// decode image size
			BitmapFactory.Options o = new BitmapFactory.Options();
			o.inJustDecodeBounds = true;
			BitmapFactory.decodeStream(new FileInputStream(f), null, o);

			// Find the correct scale value. It should be the power of 2.
			final int REQUIRED_SIZE = 70;
			int width_tmp = o.outWidth, height_tmp = o.outHeight;
			int scale = 1;
			while (true)
			{
				if (width_tmp / 2 < REQUIRED_SIZE
						|| height_tmp / 2 < REQUIRED_SIZE)
					break;
				width_tmp /= 2;
				height_tmp /= 2;
				scale *= 2;
			}

			// decode with inSampleSize
			BitmapFactory.Options o2 = new BitmapFactory.Options();
			o2.inSampleSize = scale;
			return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
		} catch (FileNotFoundException e)
		{
		}
		return null;
	}

	// Task for the queue
	private class PhotoToLoad
	{
		public String url;
		public ImageView imageView;

		public PhotoToLoad(String u, ImageView i) {
			url = u;
			imageView = i;
		}
	}

	PhotosQueue photosQueue = new PhotosQueue();

	public void stopThread()
	{
		photoLoaderThread.interrupt();
	}

	// stores list of photos to download
	class PhotosQueue
	{
		private Stack<PhotoToLoad> photosToLoad = new Stack<PhotoToLoad>();

		// removes all instances of this ImageView
		public void Clean(ImageView image)
		{
			for (int j = 0; j < photosToLoad.size();)
			{
				if (photosToLoad.get(j).imageView == image)
					photosToLoad.remove(j);
				else
					++j;
			}
		}
	}

	class PhotosLoader extends Thread
	{
		public void run()
		{
			try
			{
				while (true)
				{
					// thread waits until there are any images to load in the
					// queue
					if (photosQueue.photosToLoad.size() == 0)
						synchronized (photosQueue.photosToLoad)
						{
							photosQueue.photosToLoad.wait();
						}
					if (photosQueue.photosToLoad.size() != 0)
					{
						PhotoToLoad photoToLoad;
						synchronized (photosQueue.photosToLoad)
						{
							photoToLoad = photosQueue.photosToLoad.pop();
						}
						Bitmap bmp = getBitmap(photoToLoad.url);
						memoryCache.put(photoToLoad.url, bmp);
						String tag = imageViews.get(photoToLoad.imageView);
						if (tag != null && tag.equals(photoToLoad.url))
						{
							BitmapDisplayer bd = new BitmapDisplayer(bmp,
									photoToLoad.imageView);
							Activity a = (Activity) photoToLoad.imageView
									.getContext();
							a.runOnUiThread(bd);
						}
					}
					if (Thread.interrupted())
						break;
				}
			} catch (InterruptedException e)
			{
				// allow thread to exit
			}
		}
	}

	PhotosLoader photoLoaderThread = new PhotosLoader();

	// Used to display bitmap in the UI thread
	class BitmapDisplayer implements Runnable
	{
		Bitmap bitmap;
		ImageView imageView;

		public BitmapDisplayer(Bitmap b, ImageView i) {
			bitmap = b;
			imageView = i;
		}

		public void run()
		{
			if (bitmap != null)
				imageView.setImageBitmap(bitmap);
			else
				imageView.setImageResource(stub_id);
		}
	}

	public void clearCache()
	{
		memoryCache.clear();
		fileCache.clear();
	}

}
